1. Field of the Invention
The present invention relates generally to biomechanical sensors used for biofeedback, and in particular, to biomechanical sensors that interface with computing devices.
2. Description of the Prior Art
Inactivity and poor posture can cause significant back problems. About nine out of ten adults experience back pain at some point in their life, and five out of ten working adults have back pain every year. A. T. Patel and A. A. Ogle (2000), “Diagnosis and Management of Acute Low Back Pain”, in American Family Physician, March 15; 61(6): 1779-1786.
Back pain also exacts a huge economic cost—estimated to be over $50 billion per year in direct (e.g., health care expenditures) and indirect (e.g., lost productivity) costs. In the United States, back pain is the primary reason for job-related disability, one of the leading causes of missed work days, the primary reason for people younger than 45 to limit their activity, and the second most common reason for visits to the doctor.
Medical practitioners agree that back pain can often be reduced by maintaining good posture—that is, a “neutral spine” posture—while sitting, standing, lying, or moving. The neutral spine posture in a healthy spine is an optimal position of three natural curves of the spine: a neck (cervical) region, a mid-back (thoracic) region, and a lower-back (lumbar) region. As shown in FIG. 1, the neck region curve involves cervical vertebrae C1-C7, and is ideally anteriorly convex (i.e., should curve inward). The mid-back region curve involves thoracic vertebrae T1-T12, and is ideally posteriorly convex (i.e., should curve outward). The lower-back region curve involves lumber vertebrae L1-L5 and is ideally anteriorly convex (i.e., should curve inward).
Posture is determined to some degree by pelvic tilt. As shown in diagram 201 of FIG. 2, a neutral pelvis (i.e., a pelvis that is not tilted) indicates that anterior superior iliac spines (ASIS) and the pubic symphysis (not visible in FIG. 2) fall along a vertical line running through the leg bones, the anterior curves of the lumbar and cervical regions, and out the top of the head.
If the ASIS and pubic symphysis are not properly aligned, the pelvis is rotated and thereby changes the curvatures of the lumbar, thoracic, and/or cervical regions of the spine. When the pelvis is rotated to a forward tilting position (i.e., an anteverted position), the lumbar curvature increases beyond a neutral spine position. When this anterior rotation of the pelvis is extreme, it can result in an unhealthy swayback posture (i.e., lordosis) as shown in diagram 202. If an individual instead slouches, the pelvis rotates to a backward tilting position (i.e., a retroverted position as shown in diagram 203), thereby flattening out the cervical, thoracic, and lumbar curvatures as also shown in the figure.
Biofeedback (i.e., a process of using physiological indicators of a biological system to monitor and control behavior of that biological system) is one way to provide feedback to individuals about how their bodies are functioning, with a goal of using that information to monitor and change problematic behaviors, such as smoking and weight gain. As an example, U.S. Pat. No. 5,749,838 (Kline) discloses a posture training device which can be held against the backbone of a person by a belt or garment such that an increase in curvature of the backbone in either a midsagittal or transverse plane moves a module within a frame relative to the frame. When the module has been moved sufficiently to indicate a poor posture position, a tactile signal generator within the module is activated to vibrate, thereby alerting the person that he has assumed a poor posture.
This and other conventional biomechanical devices typically require garments or belts to hold sensors in place. It can be difficult to apply these devices in a way that people find visually appealing, comfortable, and convenient. Furthermore, these devices tend to be bulky, adding to the discomfort of wearing these devices. What is needed is a flexible, comfortable device that can measure a user's positions and movements to provide postural feedback.